<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        #two{
            color:red;
        }

        .one{
            color:green;
        }

        p{
            color:orange;
        }

        div p {
            color:yellow;
        }

        p.one {
            color:blue;
        }

    </style>
</head>
<body>

   <div id="two">
       <p class="one">
           这是一行文字
       </p>
   </div>
</body>
</html>